zero boost

Recently dealer replaced turbos under warranty, after car was running good for about 3 weeks. I went to go get some gas and got in it some and noticed no boost tried a few more times same thing nothing like the turbos were doing nothing. No sound, no whistle, bov made no noise, just nothing.

So I hooked up my cobb AP and found no codes. I then tried some pulls measuring boost nothing at all. When i did go wot the car would creep up to 4-5k and I would get a limp mode but the car ran the same no power or boost. I did finally get the 30FF code low boost. I could turn the car and off limp mode would go.

Took my car to my indie shop hoping it was a vacuum line or something from the FMIC or charge pipe but they smoked tested it replaced some vacuum lines and never saw any leaks and said it all made no sense should be getting boost and maybe it was the turbos and to take it back to the dealer.

Well I took it back to dealer and after having a couple days they said the vacuum pump turbo needs to be replaced. I have never really seen any posts on this is this plausible and does anyone have some knowledge on this? If so I would greatly appreciate it.